Optical Print Head Reference Voltage Stabilization

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Solution Overview

Problem

Existing optical print heads with multiple power feeding points still experience uneven light emission due to potential drops on power lines between adjacent points, leading to inconsistencies in light output from organic light-emitting diodes (OLEDs).

Innovation Solution

An optical print head design featuring OLEDs connected to current supply lines branching from a first power line, with holding elements and driving drivers controlling current based on stored voltages, using a separate power line for reference voltage to stabilize light emission, ensuring uniformity across all OLEDs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple power feeding points are provided on the substrate, then the wiring distance is shortened and potential drop is reduced, but unevenness in light emission amount still occurs due to potential drop between adjacent power feeding points

Engineering Contradiction:
Improveuniformity of light emission amountVSAvoidpotential drop on power line
Core Design Contradiction:
Measurement precisionVSLoss of energy

Solution Approach 1:

A moisture-proof plate is introduced as an intermediary component carrying auxiliary power lines. These auxiliary power lines connect to the substrate's power lines at multiple points, serving as a mediator to distribute power more evenly across the substrate and reduce potential drops between adjacent power feeding points.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The power distribution system is extended from a two-dimensional substrate plane to a three-dimensional structure by adding a moisture-proof plate as a separate layer. This allows auxiliary power lines to be routed on the moisture-proof plate and connect at multiple points, creating additional power feeding pathways that reduce potential drops.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Measurement precision

If auxiliary power lines are added on the moisture-proof plate, then the number of power feeding points increases, but the circuit configuration becomes more complex

Engineering Contradiction:
Improveuniformity of light emission amountVSAvoidcircuit configuration
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The moisture-proof plate serves multiple functions: it provides mechanical support for the OLED elements, acts as a barrier against moisture and contaminants, and simultaneously carries auxiliary power lines for improved power distribution. This multi-functionality reduces the need for additional separate components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The auxiliary power lines are integrated with the existing power distribution system by connecting them to the substrate's power lines at multiple points. This merging of power distribution pathways allows the system to benefit from additional power feeding points without requiring completely separate wiring systems.

Inventive Principle:
Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration effectively suppresses unevenness in light emission by stabilizing the voltage supply to each OLED, reducing potential drops and ensuring consistent light output across the print head.

Implementation Method 1

a line head including a large number of organic EL elements as light-emitting elements

Methodology Applied
Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentEP2921305B1Optical print head and image forming apparatus
Publication Date: 2016.10.19 KONICA MINOLTA INC
  • EP2921305B1 patent drawingFigure 1
  • EP2921305B1 patent drawingFigure 2~4
  • EP2921305B1 patent drawingFigure 5

AI summary

Optical print head includes: light-emitting elements connected one-to-one to current supply lines branching from first power line at different positions in longitudinal direction; holding elements; signal writing unit writing luminance signal into each holding element, the luminance signal being represented by voltage indicating light emission amount of corresponding light-emitting element; second power line supplying reference voltage to each holding element, the reference voltage being reference when signal writing unit writes luminance signal into holding element; and driving drivers corresponding one-to-one with current supply lines and controlling current supplied to corresponding current supply line from first power line, in accordance with voltage held in corresponding holding element when signal writing unit has written luminance signal into corresponding holding element, wherein power source supplying the reference voltage to second power line is common with power source supplying voltage to signal output subunit outputting luminance signal.